1. Field
This subject matter relates to hybrid propulsion. More particularly, it relates to methods and systems for hybrid propulsion for a motorized vehicle.
2. Background
Hybrid technology is recognized as an efficient bridge technology for increasing the fuel mileage of motorized vehicles by pairing conventional internal combustion engines (referred hereinafter as a “mechanical” motor or engine) with conventional electromagnetic engines (referred hereinafter as an “electrical” motor or engine). The implementation of hybrid technology is understood to come in either a series mode or parallel mode of operation.
In the series mode, the hybrid powerplant provides propulsion to the drive train exclusively through the electric motors. Though there is a mechanical motor, the mechanical motor provides no function other than running a generator to generate electricity for the battery which acts as the energy source and reservoir for supporting the electric motor(s). Therefore, in the series mode, the mechanical motor does not interface with the drive train.
Since the on-board battery is the direct source of energy for the electrical motor(s), it must be capable of storing a significant amount of energy to accommodate the vehicle's performance requirements. Under high performance conditions, the battery will be drained at a rapid rate. This problem is addressed by increasing the storage capacity of the battery and also increasing the “speed” of the mechanical motor to increase the rate of electricity being generated by the generator, thereby replenishing the battery. Nonetheless, in the series mode, the battery is understood to be necessarily large, thus becoming heavy, expensive, and unavoidably of limited lifetime.
In the parallel mode, both the mechanical engine and the electrical motor(s) engage the drive train. Depending on the driving conditions, the mechanical engine or the electrical motor (being powered by the battery) will be the only source of propulsion. Similar to the series mode, when the electrical motor(s) is running, the mechanical engine is run to replenish the battery's energy, via the generator. Consequently, the battery still remains the source of energy for the electrical motor(s). Therefore, the parallel mode suffers from the same problem of the series mode in that a large battery is required to meet all the performance requirements of the hybrid platform. The negative impact of the battery on either of these hybrid systems is evidenced by the large amount of research currently being conducted by automobile corporations into developing smaller, more powerful battery systems for running the electrical motors.
In both of these modes, when charging the battery, it is presumed that the mechanical motor will be operated at its peak efficiency so as to maximize the generation of electricity for storage in the battery. Thus, the generator is matched for the battery, not the electrical motor. Also, peak efficiency for a mechanical motor is known to be usually somewhere in the higher rpm range of the motor and not in the lower rpm range. Therefore, increased fuel costs will be incurred when charging the battery.
In view of the above implementations, hybrid methods and systems are disclosed wherein the need for a large battery or energy storage medium is obviated, as well as increased performance with the mechanical motor operating in idle, or near idle. Therefore, significant advantages can be found, including increased mileage over conventional systems.